Proposed session continuity methods in the case where a process is assigned to a server that is different from a previous server include, for instance, methods in which a correspondence table of state codes and states is held in respective servers beforehand such that, upon response to a client, a state code denoting a current state is included in a cookie and the cookie is returned, and a server that has received the cookie as a request restores the state on the basis of the state code (Japanese. Patent Application Publication No. 2002-334057).